While that attack was unfolding in texas, the showdown over gun violence in washington was haning. It was intensely personal. There's the president arm in arm with one of the teachers at sandy hook elementary. They met with lawmakers face to face, urging them to act. Reporter: The wheelers came to capitol hill today, carrying their grief and their stories of ben, their 6-year-old gunned down in his first grade class at sandy hook elementary school. David is a graphic artist. Francine a piano teacher. But they were citizen lobbyists today as they walked through the halls of congress, armed with pictures of ben and his brother nate, who heard the shooting from his fourth grade classroom. Nate survived. His little brother did not. I am thinking about ben and that he was murdered and that his brother heard it and that i have to live with that. And that is what I am thinking about. And I am here again. Like I said, I am here for them. Reporter: The wheelers and ten otr newtown families are pushing president obama's gun legislation. They went door-to-door, urging senators to pass expanded background checks and limiting the sale of high-capacity weapons like the kind that killed their children. All we ask is that you consider what we very firmly and strongly believe is the right and fair thing to do. Reporter: But did they change any minds? By the end of the day, they visited nearly a dozen senators, including johnny isakson, a georgia republican. He disagrees with their position, but believes they should be heard. You plan to vote against some of the measures that they are supporting, but you still decided to meet with them. Why? These are parents who lost their children in a terrible tragedy, and if you can't sit down and meet with those people, you shouldn't be meeting with anybody at all. What is the answer to the question you posed? Are the families moving the senators any closer to compromise on these background checks? That's really an open question. The realties of hitting these families hard. They're still threatening to filibuster. But democrats are calling the bluff. So the showdown will begin then. Now a story developing out of cuba.

This transcript has been automatically generated and may not be 100% accurate.